@@ -222,19 +222,14 @@ int elevator_init(struct request_queue *q, char *name)
if (!e) {
/*
- * For blk-mq devices, we default to using mq-deadline,
- * if available, for single queue devices. If deadline
- * isn't available OR we have multiple queues, default
- * to "none".
+ * For blk-mq devices, default to "none". udev can later set
+ * an appropriate default scheduler based on the disk
+ * characteristics which we do not yet have here.
*/
- if (q->mq_ops) {
- if (q->nr_hw_queues == 1)
- e = elevator_get("mq-deadline", false);
- if (!e)
- return 0;
- } else
- e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
+ if (q->mq_ops)
+ return 0;
+ e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
if (!e) {
printk(KERN_ERR
"Default I/O scheduler not found. " \
For blk-mq disks with a single hardware queue, setting by default the disk scheduler to mq-deadline early during the queue initialization prevents properly setting zone write locking for host managed zoned block device as the disk type is not yet known. Fix this by simply not setting the default scheduler to mq-deadline for single hardware queue disks. A udev rule can be used to easily do the same later in the system initialization sequence, when the device characteristics are known. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- block/elevator.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-)